Penny Science Experiment

This shiny penny science experiment is fun for kids of all ages. I love that you can make the pennies look better or worse! You might also enjoy these STEM activities for kids using household items.

This shiny penny science experiment is fun for kids of all ages. I love that you can make the pennies look better or worse! #stemed #scienceforkids #pennyscience #homeschool #edchat

Penny Science Experiment for Kids

This simple science experiment is fun, costs pennies, and can be done, reversed, and done again. Pretty magical!

Research Question: Why Does Copper Turn Green?

Have you ever seen a building with a copper roof that was green? The Statue of Liberty is also green because it is made out of copper. This thoroughly confused me as a child, because I knew very well that it was copper that gave pennies their distinct, very un-green color.

Copper turns green after reacting with oxygen. And that green patina actually protects copper from corrosion!

Experiment #1: Pennies and Vinegar

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Penny science experiment: The side of the pennies that was face-up from the vinegar turned green

As an oxidation experiment, we took some shiny pennies and laid them on a vinegar-soaked paper towel. After a couple of days, they turned quite green on the face-up side.

Pennies and vinegar science experiment. The side of the pennies that was touching the vinegar stayed shiny

The vinegar only sped up the oxidation of the pennies where the pennies were in contact with the vinegar. The pennies stayed shiny on the side that was against the paper towel.

Science Experiment #2: Pennies and Olive Oil

We wanted to find out if we could then remove that patina.

The side of the pennies that faced up after soaking in olive oil

We took our vinegar pennies and soaked them in olive oil for a couple of days, because I know that’s one way you can clean very old coins.

The “green” side looked a little more metallic, although the pennies definitely showed some marking from their journey.

Pennies that faced down after soaking in olive oil

The “shiny” side actually looked a little worse, especially where a couple pennies had overlapped by accident during the vinegar portion of the experiment!

Next time we’ll try lemon juice and salt for a couple days, like we read about at sunnydaytodaymama.

Have you tried this shiny penny science experiment? What did you discover?

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MaryAnne lives in Silicon Valley with her Stanford professor husband Mike and their four children. She writes about parenting through education, creativity, and play. Mama Smiles - Joyful Parenting is a space to share crafts, hands on learning activities, and family outings that enrich lives and bring families together.

12 thoughts on “Penny Science Experiment”

  1. I didn’t know that the pennies will get green – wouldn’t it apply only to really old pennies that were still made with copper? I recall reading somewhere that newer pennies don’t have copper in them. We tried to clean our pennies in vinegar solution – this was a big hit.

  2. Looks like you had some interesting results from your experiments! Sunnyboy will enjoy giving these methods a try. Thanks for linking to our cleaning coins post. :)

  3. I know a couple of people have linked up with penny leaning experiments on science Sunday I’ve seen ketchup used and UT worked fairly fast

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